Abnormal glenoid architecture resulting from loss of bone usually is listed among the contraindications to total shoulder arthroplasty using an unconstrained prosthesis. However, in a series of 463 consecutive replacement procedures that were performed between 1973 and 1985, in only two patients did the lack of bone make the implantation of a glenoid component impossible. Of the remaining sixty-five shoulders that had an abnormal glenoid, twenty were successfully treated with a large, internally fixed bone graft or grafts and forty-five, with smaller bone grafts that were not internally fixed. Nineteen of the twenty shoulders that had a large graft or grafts were followed for two years or more (average, 4.4 years). The clinical results were judged to be excellent in sixteen and satisfactory in one, and the desired limited goals were obtained in two. Two fixation screws broke and one screw was worn by contact with the humeral component. None of the glenoid components clinically loosened or migrated, and no patient has needed further surgical treatment. Although bone-grafting was necessary in only twenty (4.3 per cent) of the 463 replacement procedures, this procedure provided sufficient osseous support to allow implantation of a component in a severely damaged glenoid.